Point Level Fault Reporting
Use the diagnostic fault tables to check faults for the 1756-OA8D and 1756-OB16D diagnostic output modules:
1756-OA8D Diagnostic Fault Table
Commanded Output State to the Module | Output Data Echo & Display from the Module | No Load | Output Verify 1 | Fuse Blown 1 | Pulse Test 2 | Possible Cause of Fault |
ON OFF | OFF OFF 3 | NA NA | NA NA | Fault NA | Fail Fail | Output is shorted to GND |
ON OFF | ON OFF | NA Fault | NA NA | NA NA | Fail Pass | No Load, output is shorted to DC+, or no power to the module |
ON 4 OFF | ON OFF | NA NA | Fault NA | NA NA | Pass Fail | Hardware point damage 5 |
1) The electronic protection of this module has been designed to provide protection for the module from short circuit conditions. The protection is based on a thermal cutout principal. In the event of a short circuit condition on an output channel, that channel will limit the current within milliseconds after its thermal cutout temperature has been reached. Other channels could produce a false error on the output verify fault signal due to the supply dropping below the minimum detect level of 19.2V dc. The output channels that are affected by this phenomenon will continue to operate as directed by the module master (CPU, Bridge, etc.) What this means is that the output verify fault signals of the other channels should be checked and reset if a short circuit on one channel occurs. 2) When pulse test is executed, it is normal operation to see a momentary pulsation on the module display. 3) It is not possible to create a fuse blown fault in the OFF state. in the event of a short circuit, the output point is turned OFF and the fault will appear in the OFF state until that point is reset. 4) The output cannot turn ON due to hardware point damage. 5) During normal operating conditions, hardware damage should not be possible. See output shorted to GND as a possible cause. | ||||||
1756-OB16D Diagnostic Fault Table
Commanded Output State to the Module | Output Data Echo & Display from the Module | No Load | Output Verify 1 | Fuse Blown 1 | Pulse Test 2 | Possible Cause of Fault |
ON OFF | OFF OFF 3 | NA NA | NA NA | Fault NA | Fail Fail | Output is shorted to GND |
ON OFF | OFF OFF 3 | NA NA | NA NA | Fault NA | Fail Fail | Output is shorted to GND |
ON OFF | ON OFF | NA Fault | NA NA | NA NA | Fail Pass | No Load, output is shorted to DC+, or no power to the module |
ON 4 OFF | ON OFF | NA NA | Fault NA | NA NA | Pass Fail | Hardware point damage 5 |
1) The electronic protection of this module has been designed to provide protection for the module from short circuit conditions. The protection is based on a thermal cutout principal. In the event of a short circuit condition on an output channel, that channel will limit the current within milliseconds after its thermal cutout temperature has been reached. Other channels could produce a false error on the output verify fault signal due to the supply dropping below the minimum detect level of 19.2V dc. The output channels that are affected by this phenomena will continue to operate as directed by the module master (CPU, Bridge, etc.) What this means is that the output verify fault signals of the other channels should be checked and reset if a short circuit on one channel occurs. 2) When pulse test is executed, it is normal operation to see a momentary pulsation on the module display. 3) It is not possible to create a fuse blown fault in the OFF state. In the event of a short circuit, the output point is turned OFF and the fault appears in the OFF state until that point is reset. 4) The output cannot turn ON due to hardware point damage. 5) During normal operating conditions, hardware damage should not be possible. See output shorted to GND as a possible cause. | ||||||
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